Touch fasteners (i.e. Velcro®, Scotchmate®, Tri-Hook®, etc.) were originally produced using textile technology. Two of the most common types of touch fasteners as of this writing are hook and loop fasteners and mushroom and loop fasteners.
Hook and loop type fasteners, as they were originally developed and commercialized, consisted of a pair of textile strips. These textile strips could be mated to form a recyclable closure; one of the mates being a strip of textile fabric having numerous monofilament fastening elements, shaped like hooks, projecting from one surface and the other mate being a textile strip with multi-filamented fastening elements, woven into loop shaped projections on one surface. When the mating surfaces of these strips are pressed together, the numerous hook-shaped elements on one strip were ensnared by the loop elements on the opposing strip, creating a temporary, recyclable bond. As the strips were peeled apart, the hook elements were deformed resulting in separation from the loop elements, allowing the fasteners to be reused many times.
In the case of mushroom and loop fasteners, the hook type mating strip was replaced with a strip containing numerous monofilament projections having mushroom shaped heads. The mushroom shaped heads were formed by heating the tips of straight monofilament projections until a bulbous “mushroom head” was formed on each projection. As the strips were peeled apart, the mushroom shaped elements generally deflected and released the loop element, however, the mushroom head would often snap and destroy the loop element, thus reducing the number of times the fastener may be reused.
More recently the use of thermoplastic extrusion/molding methods for making touch fasteners has become popular. In the case of hook and loop fasteners, the hook strip may now be extruded/molded while the loop strip may be still produced using woven, knitted or non-woven fabric technologies. In the case of mushroom and loop fasteners, the mushroom strip may be produced by extruding/molding a strip of material having pin-like projections and then post-forming bulbous mushroom-like heads on the pin-like projections; the loop strip still being produced using woven, knitted or non-woven technologies.
In some instances, two mating surfaces of mushroom-like heads or bulbs may be engaged to form a fastener.
The use of extrusion/molding technologies for the production of hook type and mushroom type touch fasteners has significantly reduced the manufacturing cost and improved the performance and aesthetics of touch fasteners, thus allowing their use in large volume applications, such as tab closures on disposable diapers or for the attachment of upholstery fabrics in automotive type seating.
Both textile and molded touch fasteners are typically produced with a flat or planar base (strip) and numerous projections or loops (fastening elements) emanating from the top and/or bottom surface of the strip. These fastener strips may typically be sold in strip-like or ribbon-like form as depicted at 10, 10A in FIG. 1A and FIG. 1B.
In FIG. 1A, the fastener strip 10 is shown as generally planar and comprises a flat base 12 with a plurality of hook-like 14 or mushroom-shaped (not shown) projections emanating from one surface.
FIG. 1B illustrates the mating strip 10A which is generally planar and comprises a flat base 12A with a plurality of loops 16 emanating from one surface. Inverting strip 10 and engaging the surface with the projections with the loop surface of strip 10A forms a touch fastener.
Various cross sections of typical fastener strips are depicted in FIG. 1C through FIG. 1H below.
FIG. 1C illustrates one surface of the base 12 with hook-shaped fasteners 14 projecting therefrom.
FIG. 1D illustrates one surface of the base 12A with loops 16 emanating therefrom.
FIG. 1E illustrates hook-shaped fasteners 14 projecting from both surfaces of the base 12.
FIG. 1F illustrates loops 16 emanating from both surfaces of the base 12A.
FIG. 1G illustrates one surface of the base 12 (or 12A) with hook-shaped fasteners 14 projecting therefrom and loops 16 emanating from the opposite surface.
FIG. 1H illustrates one surface of the base 12 with mushroom-shaped fasteners 18 projecting therefrom.
FIG. 1I illustrates one surface of the base 12 with bulb-shaped fasteners 19 projecting therefrom
While the planar form of the strip that is typical in prior art fastening strips allows the fastening strip to be flexible or compliant when bent in a direction generally perpendicular to the surface of the base as depicted in FIG. 2A, it does not typically allow for compliance or flexing in a generally coplanar direction (or parallel with the plane of the base) as depicted in FIG. 2B.
FIG. 2A illustrates the strip 10 being capable of bending in a plane generally perpendicular (arrow A) to either surface of the strip 10.
FIG. 2B illustrates that the strip 10 is essentially incapable of bending in a plane parallel (arrow B) to the surface of the strip 10.
The ability of the fastener strip 10 or 10A to be bent in a geometry generally coplanar or parallel to the strip is particularly important when it is desirable to bond or mold the fastener strip to the surface of a flat object. Touch fasteners are often bonded to, or otherwise attached to objects such as room walls, toys, automotive seat cushions, etc. The surface bonded to is often generally flat or planar in nature. Bonding a straight strip of fastener to a flat surface as a simple straight strip may be relatively straightforward as the strip does not have to deform significantly to conform to the shape desired. When it is desirable to attach a fastener strip to a generally flat surface in a curved or otherwise non-straight geometry, the fastener strip is typically cut into small pieces and attached intermittently so as to create a form approximating the curve or geometry desired. Curved shapes of fasteners may be cut from large sheets of fastener product, but this often is wasteful and requires custom orders, additional inventory and advanced planning to acquire the various geometries desired.
To allow a touch fastener strip to be bent into a curved geometry, touch fasteners may often be made compliant by cutting the strip-like product intermittently along one or both sides thus producing a backbone like structure as depicted in FIG. 3A. This allows the product to be bent (arrow C) as required as depicted in FIG. 3B into a curved shape still having a flat surface. In FIGS. 3A and 3B, the projections from the surface of the strip 10B may be hooks 14, loops 16 or mushroom heads 18 or other fastening elements.
Touch fasteners may sometimes be cut into a series of discreet pieces 20 and re-joined together with a flexible center spine 22 added to join the pieces together and provide the product 10C as depicted in FIG. 4A. This allows the product to be bent and formed (arrow C) into various shapes that lie in a single plane as required as depicted in FIG. 4B. Variations of this design wherein the discrete pieces and spine are integrally molded together to produce a strip are contemplated as well.
Another method of providing a flexible strip 10D may include slits or apertures 24 that may be cut into the base 12 of the fastener strip 10D to make the strip more compliant as depicted in FIG. 5A. This allows the product to be bent (arrow C) as required as depicted in FIG. 5B.
Textile fasteners may often be produced with elastomeric fibers woven into the strip to allow the ribbon-like strip to be stretched, flexed or bent as required by an application.
Although the intermittent cutting of the edges of a fastener strip may allow it to be more compliant, this is often undesirable when the application requires a continuous fastener with a more uniform distribution of fastening elements along its' length. A typical application that would benefit from this would be the use of particularly aggressive and strong fasteners for fastening the upholstery fabric onto automotive seat cushions as depicted in FIG. 6A. In FIG. 6A, a seat 100 for an automobile may include a foam seat cushion 102 and a foam seat back 104 in an upright configuration, with a plurality of fastener strips 10 or 10A, mounted to the foam seat surface to securely fasten a seat cover 200 to the foam cushion 102, 104.
In this application, one of the fastening elements (the hook side 10 for example) is molded into or bonded onto the outer surface of a urethane seat cushion 102. The seat cover 200 is prepared with the mating material (the loop side 10A for example) in the appropriate location for mating with the hook-containing strip 10 during assembly of the cover 200 to the urethane cushion 102, 104. A cross section of a seat cushion depicting the hook 10 and loop 10A fastener strips in an overlying position ready to be engaged (arrow D) is depicted in FIG. 6B. The fastening strips may be applied to the urethane cushion as straight strips (FIG. 6A) or may be applied as curved strips to accommodate aesthetic as well as functional needs as depicted in FIG. 6C.
The fastener strips used for these automotive seating applications are often molded in place during the casting of the urethane seat cushion by inserting the fastener into the mold before the liquid urethane precursors are poured into the foaming mold. The fastener strip may generally be non-permeable to prevent the liquid urethane material from penetrating through the base of the fastening strip and contaminating the fastening elements.
The fastening strip closures used for automotive seating are also subjected to high use loads by the end user. The forces applied when an end user sits in a seat or moves around in their seat may cause the fastening strip to disengage or tear from the urethane foam seat cushion surface. It is therefore desirable to distribute these loads over a large portion of the urethane foam seat cushion surface to avoid tearing the fastener strip away from the urethane cushion during use. It is also desirable to have a high force of fastening using a minimal amount of fastener strip to the seat cushion to allow for design flexibility and reduce costs. The use of intermittent or notched fastener strips may not allow for such high forces of fastening. This may be because a significant amount of the surface of the notched fastener strip, i.e. the gap space in the fastening strip, does not contain fastening elements. The gaps or intermittent nature of the strip may be further undesirable as they reduce the bonding area with the urethane foam thereby reducing the strength of the foam to fastener bond.
Fasteners strips which are non-compliant or poorly comply with the surfaces being bonded may make the seat cushion stiff in regions local to the fastener strips. This stiffness often telegraphs through the seat covering thus making the seat uncomfortable to the end user. It is therefore desirable that the fastener strips be compliant in multiple planes to minimize or eliminate stiff or hard spots in the finished seat.
Accordingly, a need exists for a cost-effective touch fastener strip that is flexible in multiple planes yet can maintain the required fastening performance. The following disclosure describes such fastener strips and the methods for producing them. Although the terms “tape” or “strip” are used throughout the disclosure below, the present invention is not limited to these configurations for touch fasteners. Although the terms hook and loop fastener and strip are used below, any fastener that is capable of mechanical fastening is contemplated herein.